Those who related to the film industry, such as the Hollywood, are on strict guard against copying of digitized movie films. In view of the circumstances, DVDs, DVD players, and DVD recorders are provided with functionality for refraining from operations of making any copies of original works, including personal copies.
More particularly, movie content is recorded on a DVD in form of data encrypted using an encryption key that is unique to the DVD. With this arrangement, even if movie content is simply copied to another recording medium, such an unauthorized copy is not available for any use.
In addition, when outputting to a TV a progressive or interlaced video signal for movie playback, a legitimate DVD player embeds information called CGMS (CGMS-A: Copy Generation Management System-Analog in the case of analog output) into the output signals for imposing restrictions on recording. With the CGMS embedded into the content, an unauthorized recorder cannot record the video signal even if such a recorder is connected to the player.
The patent literature listed below discloses copy control technology for DVD.    [Patent Literature 1]
JP Patent No. 3162049